Copper-plated welding wire anti-corrosion pretreatment solution, anti-corrosion electroless plating solution and anti-corrosion treatment method

Abstract

The present invention relates to the technical field of anti-corrosion treatment of copper-plated welding wires, and particularly relates to a pre-treatment solution for anti-corrosion of copper-plated welding wires, an anti-corrosion electroless plating solution, and an anti-corrosion treatment method. The treatment solution is an aqueous solution containing isopropanol, oxalic acid, benzotriazole, and a surfactant. The electroless plating solution comprises the following raw materials: borax, a composite complexing agent, cobalt sulfate, sodium borohydride, 5,5-dimethylhydantoin, sodium molybdate, sodium borohydride, and hydrazine hydrate. The anti-corrosion treatment method comprises the following steps: immersing the copper-plated solid-core welding wire in the pre-treatment solution at 35-50°C and applying ultrasonic treatment; immersing the copper-plated solid-core welding wire after the pre-treatment in the electroless plating solution at 70-85°C for treatment, cleaning it thoroughly with deionized water, and then drying it. The present invention can improve the corrosion resistance of the welding wire on the premise of basically not affecting the electrical conductivity, thereby solving a series of problems caused by poor corrosion resistance, and having good economic benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of anti-corrosion treatment of copper-plated welding wires, and particularly relates to a pre-treatment solution for anti-corrosion of copper-plated welding wires, an anti-corrosion electroless plating solution, and an anti-corrosion treatment method. Background Art

[0002] In gas shielded welding, copper plating on the surface of the welding wire is mainly to improve lubricity and electrical conductivity, so as to ensure the stability of the welding process. In order to control the cost of the copper plating process, chemical plating is often used for copper plating of welding wires. However, the chemical copper plating of welding wires is essentially displacement copper plating, and copper is rapidly deposited on the surface of the welding wire through the displacement reaction between the iron matrix and copper ions under acidic conditions. However, the principle of displacement plating determines that the coating cannot completely cover the welding wire matrix, so the copper plating layer is often porous and has a relatively thin thickness. Moreover, when producing copper-plated welding wires, the welding wires are generally copper-plated first and then drawn to a predetermined diameter, and the integrity of the coating will be further reduced during the drawing process. Since the copper plating layer is a cathodic coating relative to the welding wire matrix, the copper coating that cannot completely cover the welding wire matrix accelerates the corrosion process in a humid environment. In addition, due to the insufficient antioxidant property of the copper plating layer itself, it is not suitable as a final decorative coating directly.

[0003] In order to overcome the insufficient corrosion resistance of copper-plated welding wires, at present, the corrosion resistance of copper-plated welding wires is mainly improved by means of strengthening post-treatment, such as passivating the copper plating layer. However, the passivation process of the copper plating layer often adopts the method of organic self-assembly, and the passivation layer does not have sufficient strength to cope with the repeated friction during the storage and use of the welding wire, and the anti-corrosion effect after passivation still cannot reach a satisfactory effect. Therefore, developing an anti-corrosion treatment method that can effectively improve the corrosion resistance of copper-plated welding wires is of great significance for the practical application of copper-plated welding wires. Summary of the Invention

[0004] Aiming at the problems of incomplete copper plating layer, exposure of the welding wire matrix, and poor antioxidant property of the copper plating layer during the drawing and sizing process of copper-plated welding wires, resulting in serious degradation of the corrosion resistance of the welding wire during storage, the present invention develops a pre-treatment solution for anti-corrosion of copper-plated welding wires, an anti-corrosion electroless plating solution, and an anti-corrosion treatment method.

[0005] The technical solution for the present invention to solve the technical problem is: on the one hand, the present invention provides a pre-treatment solution for anti-corrosion of copper-plated welding wires, and this treatment solution is an aqueous solution containing isopropanol, oxalic acid, benzotriazole, and a surfactant.

[0006] As an optimization, the surfactant is one of sodium dodecyl sulfate, sodium dodecyl sulfonate, or cetyltrimethylammonium bromide.

[0007] As an optimization, the weight-volume ratio of this treatment solution is as follows: oxalic acid 20 - 30 g: benzotriazole 1 - 3 g: surfactant 2 - 3 g: isopropanol 10 - 30 L.

[0008] As an optimization, the preparation method of the pretreatment solution is as follows: Measure 10 - 30 mL of isopropyl alcohol and dissolve it in 900 mL of deionized water. Then dissolve 20 - 30 g of oxalic acid, 1 - 3 g of benzotriazole, and 2 - 3 g of surfactant in sequence, and finally make up the volume to 1000 mL to prepare the pretreatment solution.

[0009] On the other hand, an embodiment of the present invention provides an anticorrosive electroless plating solution for copper-plated welding wires. Each 1000 ml of the electroless plating solution comprises the following raw materials: 10.0 - 15.0 g of borax, 60 - 100 g of a composite complexing agent, 30 - 50 g of cobalt sulfate, 0.5 g of sodium borohydride, 20 - 30 g of 5,5-dimethylhydantoin, 2 - 5 g of sodium molybdate, 0.2 - 0.3 g of sodium borohydride, and 30 - 50 mL of hydrazine hydrate.

[0010] As an optimization, the composite complexing agent is a combination of any two of ethylenediamine, ammonium chloride, sodium potassium tartrate, or trisodium citrate.

[0011] As an optimization, its preparation method is as follows:

[0012] 1) Weigh 10.0 - 15.0 g of borax and 60 - 100 g of the composite complexing agent respectively, dissolve them in 800 mL of deionized water, and adjust the pH to 11.5 - 12.5 with potassium hydroxide.

[0013] 2) Slowly add 30 - 50 g of cobalt sulfate, stir to dissolve it, and then add 0.5 g of sodium borohydride.

[0014] 3) Heat the solution to 60 - 80 °C, and then dissolve 120 - 150 g of thiourea, 30 - 50 g of potassium thiocyanate, 20 - 30 g of 5,5-dimethylhydantoin, 2 - 5 g of sodium molybdate, 0.2 - 0.3 g of sodium borohydride, and 30 - 50 mL of hydrazine hydrate in sequence while stirring.

[0015] 4) Cool to room temperature and then make up the volume to 1000 mL to prepare the electroless plating solution.

[0016] On the other hand, an anticorrosive treatment method for copper-plated welding wires includes the following steps:

[0017] 1) Pretreatment: Immerse the copper-plated solid core welding wire in the pretreatment solution at 35 - 50 °C and apply ultrasonic treatment, then clean it with deionized water to complete the pretreatment.

[0018] 2) Electroless plating and sealing passivation of the copper-plated solid core welding wire: Immerse the copper-plated solid core welding wire after the pretreatment in the electroless plating solution at 70 - 85 °C for treatment, then clean it with deionized water, and then dry it.

[0019] As an optimization, in step 1), treat it in the pretreatment solution for 1 - 2 minutes.

[0020] As an optimization, it is treated in the electroless plating solution for 3 - 5 minutes and baked at 120 - 150 °C for 10 minutes.

[0021] Since the copper plating layer on the surface of the copper - plated welding wire often has poor oxidation resistance and cannot completely cover the welding wire substrate, the present invention utilizes the principle that electroless plating can form a uniform and continuous covering layer on the conductor surface to improve the corrosion resistance of the copper - plated welding wire. The pretreatment solution of the present invention can effectively remove the rust on the welding wire substrate that is not covered by the copper plating layer of the copper - plated welding wire. Through isopropyl alcohol and surfactant in the pretreatment solution, assisted by ultrasonic treatment, the pretreatment solution can effectively infiltrate the surface of the welding wire; through the combined action of oxalic acid and benzotriazole in the pretreatment solution, not only can the rust in the pores of the copper plating layer of the copper - plated welding wire be removed during the pretreatment process to prevent affecting the overall integrity of the sealing layer during subsequent electroless plating sealing treatment, but also the copper plating layer and the welding wire substrate can be effectively inhibited from corrosion.

[0022] Since the surface of copper has no catalytic activity for the oxidation of the reducing agent for electroless cobalt plating, it is usually difficult to directly perform electroless cobalt plating on the surface of the copper - plated welding wire. During the preparation of the electroless plating solution in the present invention, by adding a large amount of thiourea, potassium thiocyanate, and 5,5 - dimethylhydantoin to the solution, they can act as strong complexing agents for cuprous ions, causing the potential of copper to shift negatively, and the electrochemical activity to reverse with cobalt. First, a thin layer of cobalt is displaced as the catalytic layer for subsequent electroless cobalt plating. Thiourea is generally considered as a stabilizer for electroless cobalt plating and also a poison. In the process of electroless cobalt plating using sodium hypophosphite as the reducing agent, thiourea can inhibit the catalytic oxidation of sodium hypophosphite, thus terminating the electroless plating process. The present invention uses sodium borohydride and hydrazine hydrate with stronger reducibility and activity as reducing agents. They are in a metastable state when the pH is lower than 12 and are very easy to decompose on the surface of cobalt. Experimental verification shows that even a large amount of thiourea still cannot completely inhibit the oxidation process of sodium borohydride and hydrazine hydrate. Therefore, by selecting strong reducing agents, while ensuring the addition of substances such as thiourea in the solution to achieve displacement cobalt plating on the surface of the copper - plated welding wire, the next step of autocatalytic cobalt plating can be carried out, so that the coating can completely cover the copper - plated welding wire to obtain an electroless plating sealing layer and avoid the exposure of the welding wire substrate. Moreover, since sulfur, molybdenum, and boron elements are prone to co - deposit with cobalt elements, and the electroless plating solution contains a large amount of sulfur - containing compounds, the obtained electroless plating sealing layer is a cobalt - sulfur - molybdenum - boron alloy coating, and the sulfur content in the coating is very high. When the electroless plating sealing layer with a high sulfur content is baked at 120 - 150 °C for 10 minutes, the electroless plating sealing layer will undergo self - passivation, and the cobalt - sulfur - molybdenum - boron alloy coating will be transformed into a highly dense oxide layer, effectively improving the oxidation resistance. Moreover, the obtained sealing and passivation layer has higher hardness, strength, and conductivity compared with the traditional organic passivation layer, which is beneficial to the long - term storage of the welding wire and the improvement of the stability during the welding process.

[0023] The effects provided in the summary of the invention are only the effects of the embodiments, rather than all the effects of the invention. The above technical solutions have the following advantages or beneficial effects:

[0024] It is possible to improve the corrosion resistance of the welding wire without substantially affecting the electrical conductivity, thereby solving a series of problems caused by poor corrosion resistance and having good economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention.

[0026] Figure 1 is the microscopic morphology of the copper-plated welding wire before anti-corrosion treatment;

[0027] Figure 2 is the microscopic morphology of the closed passivation layer after anti-corrosion treatment in Experiment 1;

[0028] Figure 3 is the surface element distribution map of the closed passivation layer after anti-corrosion treatment in Experiment 1;

[0029] Figure 4 is the comparison of the electrochemical impedance spectra of the copper-plated welding wire before and after anti-corrosion treatment;

[0030] Figure 5 is the comparison of the Tafel curves of the copper-plated welding wire before and after anti-corrosion treatment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0032] An anti-corrosion pretreatment solution for copper-plated welding wire, the treatment solution is an aqueous solution containing isopropanol, oxalic acid, benzotriazole and a surfactant. The composition of the treatment solution is: isopropanol 7.85 - 23.56 g / l, oxalic acid 20 - 30 g / l, benzotriazole 1 - 3 g / l, surfactant 2 - 3 g / l, and the balance is water. The surfactant is one of sodium dodecyl sulfate, sodium dodecyl sulfonate or cetyltrimethylammonium bromide.

[0033] An anti-corrosion electroless plating solution for copper-plated welding wire. Each 1000 ml of the electroless plating solution comprises the following raw materials: 10.0 - 15.0 g of borax, 60 - 100 g of a composite complexing agent, 30 - 50 g of cobalt sulfate, 0.5 g of sodium borohydride, 20 - 30 g of 5,5-dimethylhydantoin, 2 - 5 g of sodium molybdate, 0.2 - 0.3 g of sodium borohydride, and 30 - 50 mL of hydrazine hydrate. The composite complexing agent is a combination of any two of ethylenediamine, ammonium chloride, sodium potassium tartrate, or trisodium citrate.

[0034] The preparation method of the anti-corrosion electroless plating solution for copper-plated welding wire is as follows:

[0035] 1) Weigh 10.0 - 15.0 g of borax and 60 - 100 g of the composite complexing agent respectively, dissolve them in 800 mL of deionized water, and adjust the pH to 11.5 - 12.5 using potassium hydroxide.

[0036] 2) Slowly add 30 - 50 g of cobalt sulfate, and after stirring and dissolving, add 0.5 g of sodium borohydride.

[0037] 3) Heat the solution to 60 - 80 °C, and then dissolve 120 - 150 g of thiourea, 30 - 50 g of potassium thiocyanate, 20 - 30 g of 5,5-dimethylhydantoin, 2 - 5 g of sodium molybdate, 0.2 - 0.3 g of sodium borohydride, and 30 - 50 mL of hydrazine hydrate in sequence under stirring.

[0038] 4) Cool to room temperature and make up the volume to 1000 mL to obtain the electroless plating solution.

[0039] Example 1

[0040] An anti-corrosion treatment method for copper-plated welding wire, comprising the following steps:

[0041] 1) Preparation of the pretreatment solution: Measure 10 - 30 mL of isopropyl alcohol and dissolve it in 900 mL of deionized water. Then dissolve 20 - 30 g of oxalic acid, 1 - 3 g of benzotriazole, and 2 - 3 g of surfactant in sequence, and make up the volume to 1000 mL to obtain the pretreatment solution.

[0042] 2) Preparation of the electroless plating solution: Weigh 10.0 - 15.0 g of borax and 60 - 100 g of the composite complexing agent respectively, dissolve them in 800 mL of deionized water, adjust the pH to 11.5 - 12.5 using potassium hydroxide, then slowly add 30 - 50 g of cobalt sulfate. After stirring and dissolving, add 0.5 g of sodium borohydride. Then heat the solution to 60 - 80 °C and dissolve 120 - 150 g of thiourea, 30 - 50 g of potassium thiocyanate, 20 - 30 g of 5,5-dimethylhydantoin, 2 - 5 g of sodium molybdate, 0.2 - 0.3 g of sodium borohydride, and 30 - 50 mL of hydrazine hydrate in sequence under stirring. Cool to room temperature and make up the volume to 1000 mL to obtain the electroless plating solution.

[0043] 3) Pretreatment: The temperature of the pretreatment solution prepared in step 1) is 35 - 50°C. Immerse the copper-plated solid cored wire in the pretreatment solution and apply ultrasonic treatment. After treating for 1 - 2 minutes, clean it with deionized water to complete the pretreatment;

[0044] 4) Chemical plating sealing passivation of the copper-plated solid cored wire: The temperature of the electroless plating solution prepared in step 2) is 70 - 85°C. Immerse the copper-plated solid cored wire after the treatment in step 3) in the electroless plating solution and treat for 3 - 5 minutes, then clean it with deionized water. After baking at 120 - 150°C for 10 minutes, complete the chemical plating sealing passivation of the copper-plated solid cored wire.

[0045] In this embodiment, isopropanol and surfactant in the pretreatment solution are assisted by ultrasonic treatment, which can effectively wet the surface of the wire by the pretreatment solution; through the combined action of oxalic acid and benzotriazole in the pretreatment solution, not only can the rust in the pores of the copper plating layer of the copper-plated wire be removed during the pretreatment process to prevent affecting the overall integrity of the sealing layer during the subsequent chemical plating sealing treatment, but also can effectively inhibit the corrosion of the copper plating layer and the wire substrate. In this embodiment, a large amount of thiourea, potassium thiocyanate and 5,5-dimethylhydantoin are added to the electroless plating solution as strong complexing agents for monovalent copper ions, so that the electrochemical activity of copper is reversed with cobalt, and a thin layer of cobalt is first replaced as the catalytic layer for subsequent electroless plating of cobalt. In this embodiment, sodium borohydride and hydrazine hydrate with strong reducibility and activity are used as reducing agents, and they will not be inhibited by a large amount of thiourea during the oxidation process when the pH is lower than 12, so that the role of the reducing agent can be exerted. While realizing displacement plating of cobalt, autocatalytic plating of cobalt can be carried out in the next step, so that the coating can completely cover the copper-plated wire, and a cobalt sulfur molybdenum boron alloy coating can be obtained. After baking treatment, the chemical plating sealing layer self-passivates to form a highly dense oxide layer, which not only has higher antioxidant properties, but also has higher hardness, strength and conductivity compared with the traditional organic passivation layer.

[0046] The following tests are used to verify that the present invention has beneficial effects when used for the anti-corrosion treatment of copper-plated wires:

[0047] Comparative test 1:

[0048] An anti-corrosion treatment method for copper-plated wires is carried out according to the following steps:

[0049] (1) Preparation of the pretreatment solution: Measure 10 mL of isopropanol and dissolve it in 900 mL of deionized water, then dissolve 30 g of oxalic acid and 3 g of sodium dodecyl sulfate in sequence and make up the volume to 1000 mL to prepare the pretreatment solution;

[0050] (2) Preparation of electroless plating solution: Weigh 10.0 g of borax and 100 g of composite complexing agent respectively, dissolve them in 800 mL of deionized water, adjust the pH to 11.5 with potassium hydroxide, then slowly add 50 g of cobalt sulfate, stir to dissolve, add 0.5 g of sodium borohydride, then heat the solution to 80 °C and successively dissolve 150 g of thiourea, 50 g of potassium thiocyanate, 30 g of 5,5-dimethylhydantoin, 2 g of sodium molybdate, 0.3 g of sodium borohydride and 30 mL of hydrazine hydrate under stirring. After cooling to room temperature, make up the volume to 1000 mL to prepare the electroless plating solution; the composite complexing agent is a combination of ethylenediamine and ammonium chloride;

[0051] (3) Pretreatment: Keep the temperature of the pretreatment solution prepared in step (1) constant at 35 °C, immerse the copper-plated solid wire in the pretreatment solution and apply ultrasonic treatment. After 2 minutes of treatment, wash it clean with deionized water to complete the pretreatment;

[0052] (4) Chemical plating, sealing and passivation of copper-plated solid wire: Keep the temperature of the electroless plating solution prepared in step (2) constant at 70 °C, immerse the copper-plated solid wire after the treatment in step (3) in the electroless plating solution for 5 minutes, then wash it clean with deionized water, and bake it at 120 °C for 10 minutes to complete the chemical plating, sealing and passivation of the copper-plated solid wire.

[0053] Comparative experiment 2: A method for anti-corrosion treatment of copper-plated welding wire is carried out according to the following steps:

[0054] (1) Preparation of pretreatment solution: Measure 10 mL of isopropyl alcohol and dissolve it in 900 mL of deionized water, then successively dissolve 30 g of oxalic acid, 3 g of benzotriazole and 3 g of sodium dodecyl sulfate, and make up the volume to 1000 mL to prepare the pretreatment solution;

[0055] (2) Preparation of electroless plating solution: Weigh 10.0 g of borax and 100 g of composite complexing agent respectively, dissolve them in 800 mL of deionized water, adjust the pH to 11.5 with potassium hydroxide, then slowly add 50 g of cobalt sulfate, stir to dissolve, add 0.5 g of sodium borohydride, then heat the solution to 80 °C and successively dissolve 50 g of potassium thiocyanate, 30 g of 5,5-dimethylhydantoin, 2 g of sodium molybdate, 0.3 g of sodium borohydride and 30 mL of hydrazine hydrate under stirring. After cooling to room temperature, make up the volume to 1000 mL to prepare the electroless plating solution; the composite complexing agent is a combination of ethylenediamine and ammonium chloride;

[0056] (3) Pretreatment: Keep the temperature of the pretreatment solution prepared in step (1) constant at 35 °C, immerse the copper-plated solid wire in the pretreatment solution and apply ultrasonic treatment. After 2 minutes of treatment, wash it clean with deionized water to complete the pretreatment;

[0057] (4) Chemical plating sealing passivation of copper-plated solid cored wire: The temperature of the chemical plating solution prepared in step (2) is kept constant at 70 °C. After the copper-plated solid cored wire processed in step (3) is immersed in the chemical plating solution for 5 minutes, it is washed clean with deionized water, and then baked at 120 °C for 10 minutes to complete the chemical plating sealing passivation of the copper-plated solid cored wire.

[0058] Experiment 1: A method for anti-corrosion treatment of a copper-plated welding wire in this experiment is carried out according to the following steps:

[0059] (1) Preparation of pretreatment solution: Measure 10 mL of isopropyl alcohol and dissolve it in 900 mL of deionized water, then dissolve 30 g of oxalic acid, 3 g of benzotriazole and 3 g of sodium dodecyl sulfate in sequence and make up the volume to 1000 mL to prepare the pretreatment solution;

[0060] (2) Preparation of chemical plating solution: Weigh 10.0 g of borax and 100 g of composite complexing agent respectively and dissolve them in 800 mL of deionized water. Adjust the pH to 11.5 with potassium hydroxide and then slowly add 50 g of cobalt sulfate. After stirring and dissolving, add 0.5 g of sodium borohydride. Then heat the solution to 80 °C and dissolve 150 g of thiourea, 50 g of potassium thiocyanate, 30 g of 5,5-dimethylhydantoin, 2 g of sodium molybdate, 0.3 g of sodium borohydride and 30 mL of hydrazine hydrate in sequence under stirring. After cooling to room temperature, make up the volume to 1000 mL to prepare the chemical plating solution; wherein the composite complexing agent is a combination of ethylenediamine and ammonium chloride;

[0061] (3) Pretreatment: Keep the temperature of the pretreatment solution prepared in step (1) constant at 35 °C. Immerse the copper-plated solid cored wire in the pretreatment solution and apply ultrasonic treatment. After 2 minutes of treatment, wash it clean with deionized water to complete the pretreatment;

[0062] (4) Chemical plating sealing passivation of copper-plated solid cored wire: The temperature of the chemical plating solution prepared in step (2) is kept constant at 70 °C. After the copper-plated solid cored wire processed in step (3) is immersed in the chemical plating solution for 5 minutes, it is washed clean with deionized water, and then baked at 120 °C for 10 minutes to complete the chemical plating sealing passivation of the copper-plated solid cored wire.

[0063] Comparison Figure 1 and Figure 2 It can be seen that the copper plating layer on the surface of the original copper-plated welding wire cannot completely cover the substrate, while the sealing passivation layer can completely cover the protective welding wire after anti-corrosion treatment, which is beneficial to the improvement of corrosion resistance. Through Figure 3 It can be seen that Ni, S, B, Mo and O elements can be evenly covered on the surface of the welding wire.

[0064] Experiment 2: A method for anti-corrosion treatment of a copper-plated welding wire in this experiment is carried out according to the following steps:

[0065] (1) Preparation of the pretreatment solution: Measure 30 mL of isopropanol and dissolve it in 900 mL of deionized water. Then, sequentially dissolve 20 g of oxalic acid, 1 g of benzotriazole, and 2 g of cetyltrimethylammonium bromide, and make up the volume to 1000 mL to obtain the pretreatment solution.

[0066] (2) Preparation of the electroless plating solution: Weigh 15.0 g of borax and 60 g of the composite complexing agent respectively, dissolve them in 800 mL of deionized water, adjust the pH to 12.5 with potassium hydroxide, then slowly add 30 g of cobalt sulfate, stir to dissolve, add 0.5 g of sodium borohydride, then heat the solution to 60 °C, and sequentially dissolve 120 g of thiourea, 30 g of potassium thiocyanate, 20 g of 5,5-dimethylhydantoin, 5 g of sodium molybdate, 0.2 g of sodium borohydride, and 50 mL of hydrazine hydrate under stirring. After cooling to room temperature, make up the volume to 1000 mL to obtain the electroless plating solution; the composite complexing agent is a combination of ethylenediamine and trisodium citrate.

[0067] (3) Pretreatment: Keep the temperature of the pretreatment solution prepared in step (1) constant at 50 °C, immerse the copper-plated solid cored wire in the pretreatment solution and apply ultrasonic treatment. After 1 minute of treatment, wash it clean with deionized water to complete the pretreatment.

[0068] (4) Chemical plating, sealing, and passivation of the copper-plated solid cored wire: Keep the temperature of the electroless plating solution prepared in step (2) constant at 85 °C, immerse the copper-plated solid cored wire after the treatment in step (3) in the electroless plating solution for 3 minutes, then wash it clean with deionized water, and bake it at 150 °C for 10 minutes to complete the chemical plating, sealing, and passivation of the copper-plated solid cored wire.

[0069] Experiment 3: A surface modification method for a copper-plated solid cored wire in this experiment is carried out according to the following steps:

[0070] (1) Preparation of the pretreatment solution: Measure 20 mL of isopropanol and dissolve it in 900 mL of deionized water. Then, sequentially dissolve 25 g of oxalic acid, 2 g of benzotriazole, and 2.5 g of sodium dodecyl sulfonate, and make up the volume to 1000 mL to obtain the pretreatment solution.

[0071] (2) Preparation of electroless plating solution: Weigh 12.0 g of borax and 80 g of composite complexing agent respectively, dissolve them in 800 mL of deionized water, adjust the pH to 12.0 with potassium hydroxide, then slowly add 35 g of cobalt sulfate, stir to dissolve, add 0.5 g of sodium borohydride, then heat the solution to 70 °C and successively dissolve 130 g of thiourea, 38 g of potassium thiocyanate, 26 g of 5,5-dimethylhydantoin, 3 g of sodium molybdate, 0.3 g of sodium borohydride and 35 mL of hydrazine hydrate under stirring. After cooling to room temperature, make up the volume to 1000 mL to prepare the electroless plating solution; the composite complexing agent is a combination of ammonium chloride and sodium potassium tartrate;

[0072] (3) Pretreatment: Keep the temperature of the pretreatment solution prepared in step (1) constant at 40 °C, immerse the copper-plated solid core wire in the pretreatment solution and apply ultrasonic treatment. After treatment for 2 minutes, wash it clean with deionized water to complete the pretreatment;

[0073] Table 2 Comparison of corrosion resistance and corrosion current of copper-plated welding wire before and after anti-corrosion treatment

[0074]

[0075] It can be shown from Table 2 that the corrosion resistance of the copper-plated welding wire after the anti-corrosion treatment in Experiments 1 to 3 is significantly improved, which is beneficial to the long-term storage of the welding wire and the improvement of the stability of the subsequent welding process; while the corrosion resistance of the copper-plated welding wire after the anti-corrosion treatment in Comparative Experiment 1 and Comparative Experiment 2 is not significantly improved.

[0076] Although the specific implementation manners of the invention are described above in conjunction with the accompanying drawings, it is not a limitation to the protection scope of the invention. Based on the technical solutions of the invention, various modifications or deformations that can be made by those skilled in the art without creative efforts are still within the protection scope of the invention.

Claims

1. A method for anti-corrosion treatment of copper-plated welding wire, characterized in that, It includes the following steps: 1) Pretreatment: Immerse the copper-plated solid wire in the copper-plated wire anti-corrosion pretreatment solution at 35 - 50 °C and apply ultrasonic treatment, then clean it with deionized water to complete the pretreatment; 2) Chemical plating and sealing passivation of the copper-plated solid wire: Immerse the copper-plated solid wire after the pretreatment in the copper-plated wire anti-corrosion chemical plating solution at 70 - 85 °C for treatment, clean it with deionized water, and then dry it; The copper-plated wire anti-corrosion pretreatment solution is an aqueous solution containing isopropanol, oxalic acid, benzotriazole and surfactant; In the copper-plated wire anti-corrosion chemical plating solution, the mass-volume ratio of borax, complex chelating agent, cobalt sulfate, 5,5-dimethylhydantoin, sodium molybdate, sodium borohydride and hydrazine hydrate is: (10.0 - 15.0) g : (60 - 100) g : (30 - 50) g : (20 - 30) g : (2 - 5) g : (0.7 - 0.8) g : (30 - 50) mL.

2. The anti-corrosion treatment method of the copper-plated welding wire according to claim 1, characterized in that In step 1), treat it in the copper-plated wire anti-corrosion pretreatment solution for 1 - 2 minutes.

3. The anti-corrosion treatment method of the copper-plated welding wire according to claim 1, characterized in that, In step 2), treat it in the copper-plated wire anti-corrosion chemical plating solution for 3 - 5 minutes, and bake it at 120 - 150 °C for 10 minutes.

4. The anti-corrosion treatment method of the copper-plated welding wire according to claim 1, characterized in that, In the copper-plated wire anti-corrosion pretreatment solution, the mass-volume ratio of oxalic acid, benzotriazole, surfactant and isopropanol is (20 - 30) g : (1 - 3) g : (2 - 3) g : (10 - 30) mL.

5. The anti-corrosion treatment method of the copper-plated welding wire according to claim 1, characterized in that The preparation method of the copper-plated wire anti-corrosion pretreatment solution is as follows: Measure 10 - 30 mL of isopropanol and dissolve it in 900 mL of deionized water, then dissolve 20 - 30 g of oxalic acid, 1 - 3 g of benzotriazole and 2 - 3 g of surfactant in sequence and make up the volume to 1000 mL to prepare the copper-plated wire anti-corrosion pretreatment solution.

6. The anti-corrosion treatment method of the copper-plated welding wire according to claim 1, characterized in that, The surfactant is one of sodium dodecyl sulfate, sodium dodecyl sulfonate or cetyltrimethylammonium bromide.

7. The anti-corrosion treatment method of the copper-plated welding wire according to claim 1, characterized in that, The complex chelating agent is a combination of any two of ethylenediamine, ammonium chloride, sodium potassium tartrate or trisodium citrate.

8. The anti-corrosion treatment method of the copper-plated welding wire according to claim 1, characterized in that The preparation method of the copper-plated wire anti-corrosion chemical plating solution is as follows: 1) Weigh 10.0 - 15.0 g of borax and 60 - 100 g of complex chelating agent respectively and dissolve them in 800 mL of deionized water, and adjust the pH to 11.5 - 12.5 with potassium hydroxide; 2) Slowly add 30 - 50 g of cobalt sulfate, stir and dissolve it, and then add 0.5 g of sodium borohydride; 3) Heat the solution to 60 - 80 °C, and then dissolve 120 - 150 g of thiourea, 30 - 50 g of potassium thiocyanate, 20 - 30 g of 5,5-dimethylhydantoin, 2 - 5 g of sodium molybdate, 0.2 - 0.3 g of sodium borohydride and 30 - 50 mL of hydrazine hydrate in sequence while stirring; 4) Cool it to room temperature and make up the volume to 1000 mL to prepare the copper-plated wire anti-corrosion chemical plating solution.

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